Publications cited throughout this disclosure are incorporated herein by reference.
The microbial-derived material referred to as "K-252a" is a unique compound which has gained significant attention over the past several years due to the variety of functional activities which it possesses. K-252a is an indolocarbazole alkaloid that was originally isolated from a Nocordiosis sp. culture (Kase, H. et al. 39 J. Antibiotics 1059, 1986). K-252a is an inhibitor of several enzymes, including protein kinase C ("PKC") and trk tyrosine kinase. The reported functional activities of K-252a are numerous and diverse: tumor inhibition (U.S. Pat. Nos. 4,877,776 and 5,063,330; European Publication 238,011 in the name of Nomato); anti-insecticidal activity (U.S. Pat. No. 4,735,939); inhibition of inflammation (U.S. Pat. No. 4,816,450); treatment of diseases associated with neuronal cells (WIPO Publication WO 94/02488, published Feb. 3, 1994 in the names of Cephalon, Inc. and Kyowa Hakko Kogyo Co., Ltd.).
The reported indolocarbazoles share several common attributes: in particular, each comprises three five member rings which all include a nitrogen moiety; staurosporine (derived from Streptomyces sp.) and K-252a (derived from Nocordiosis sp.) each further comprise a sugar moiety linked via two N-glycosidic bonds. Both K-252a and staurosporine have been extensively studied with respect to their utility as therapeutic agents. The indolocarbazoles are generally lypophilic which allows for their comparative ease in crossing biological membranes, and, unlike proteinaceous materials, they manifest a longer in vivo half life.
While K-252a possesses such varied and useful activities, a drawback to the compound is that because it is of microbial origin, it must be derived from culture media via a fermentation process; the literature indicates that K-252a has never been chemically synthesized. Accordingly, compounds which possess the desired functional activities of K-252a but which can be readily derived using chemical synthesis techniques would offer several unique and distinct advantages over the types of carbazole compounds currently available to the art.